Traditionally, compensating an accessory, such as a probe, in a test and measurement system involves removing the accessory from a device under test (DUT) and connecting the accessory to a calibrating or compensation stimulus. Conventionally, the test and measurement system includes a host, a controller, and a device under test. An accessory is attached to the device under test and measures a signal from the device under test and sends it back to the host. However, to compensate the accessory, the accessory has to be removed from the device under test and attached to a calibration/compensation stimulus, typically located on the host. Connecting the probe/accessory to the calibration or compensation stimulus may involve the use of special adapters and fixtures to interface between probe/accessory and the stimulus signal.
Using optical sensors to accurately measure down to DC has not had much success in the past. Optical sensors are susceptible to changes in the surrounding environment. Temperature, mechanical stress, and the signals applied to the optical sensor can cause the DC/LF offset component of the sensor to shift dramatically making it unusable or result in significant measurement errors.
What is needed is the ability to dynamically calibrate or compensate an accessory in real time, while it is operating, to eliminate the need to manually connect the accessory to a calibration or compensation signal and also the need to remove the accessory from a DUT to calibrate or compensate the probe. This dynamic compensation should be transparent to the user.